The attachment of particles onto a surface of a semiconductor substrate (hereinafter, referred to as “wafer”) is one of the reasons for deteriorating a production yield in a semiconductor manufacturing process. The particles are foreign materials to an integrated circuit, making the quality thereof unacceptable. Conventionally, a particle size that deteriorates the production yield is, e.g., about 50 nm to 70 nm, and can be detected by a surface inspection device such as a Surfscan or the like.
Recently, a trend towards high integration of chips is accelerated in a semiconductor industry, and this leads to a demand for a line width of an integrated circuit which is smaller than or equal to, e.g., about 50 nm. Therefore, a particle size that affects an integrated circuit becomes smaller, and it is expected that the particle size affecting the integrated circuit becomes about 20 nm or less in a near future.
A detection limit of a fine particle measuring device as a present surface inspection device is, e.g., about 40 nm. Therefore, it is expected that it will be difficult to detect particles as foreign materials attached onto a wafer surface in the near future. In that case, it is not possible to manage the condition in an accommodation chamber of a substrate processing apparatus for performing a predetermined process on a substrate such as a wafer or the like, so that a yield of product substrates deteriorates.
To that end, there is suggested in, e.g., Japanese Patent Laid-open Publication No. 2007-273947, a substrate surface inspecting method for detecting even fine particles, which may cause problem in the future, by using the present surface inspection device.
Japanese Patent Laid-open Publication No. 2007-273947 discloses a method for indirectly detecting particles on a substrate surface. In this method, water in the atmosphere surrounding a wafer onto which particles having a diameter of about 30 μm are attached is put into a supercooled state by supercooling the wafer to a temperature lower than or equal to, e.g., about −20° C. Next, the supercooled water is attached around the particles on the surface of the wafer. Thereafter, the collected supercooled water is released from the supercooled state and thus freezes, so that the frozen water grows in an ice crystal having the particle as a core and the ice crystal is detected.
In the prior art, however, the ice crystal is not always stable. Thus, when the substrate on which the particles are emphasized by the ice crystal attached thereto is transferred from a surface processing apparatus as a pre-processing apparatus to a surface inspection device for detecting particles, the ice crystal is molten to be removed. In order to protect the snow crystal-shaped frozen water, it is considered to spray, e.g., cyanoacrylate thereto. However, a reaction product of cyanoacrylate and water (snow crystal) is stable and thus cannot be decomposed. Accordingly, the substrate that has been subjected to the surface inspection cannot be restored to the original state, which prevents the inspected substrate from being subjected to another inspection or from being used as a product.